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Exchange (manually) the authorization code for a re-usable access token fails sometimes
I have integrated the Dropbox API into my .NET software.
In order for the user to link his account with the dropbox folder used by my software, my software gives the user a URL that he enters ...
Greg-DB
Dropbox Staff
Dropbox StaffWe'll be happy to help with this, but we'll need some more information about where and how this is failing. For example, is it failing on the call to /oauth2/token, and what error response are you getting? Thanks in advance!
Ok so the only information I have is that when it fails, I get this message from your API:
Type = Dropbox.Api.OAuth2Exception
Message = invalid_grant
Source = Microsoft.Threading.Tasks
ErrorDescription = code has expired (within the last hour)
What I noticed was that the client had a wrong time in its clock.
After synchronizing with the internet time, it worked.
So I am assuming that your API uses the client time for the authentication, which if its true, its a very odd decision.
Could you clarify whether this is the case, or it was just a coincidence that it worked?
- Greg-DB
I don't believe the Dropbox API OAuth 2 authorization code exchange uses the client's time. In fact, the client isn't supposed to send its client time in the /oauth2/token HTTP request anyway.
The authorization code itself does expire though, after a few minutes (based on the Dropbox server time when the code was issued versus when it is sent back for exchange). It sounds like you just happened to use it after the expiration the first time.
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